Value of Wetlands

Wetlands are found all across the state, and many are forested. Wetlands include
marshes, bogs, and swamps, and may include other areas which are only flooded
or saturated for fairly short periods of time. Nontidal wetlands are identified
on the ground by the presence of wetland hydrology, wetland soils, and wetland
vegetation. Wetlands provide many benefits:

Flood Control
Flood water flows naturally into stream and river channels as it drains off
the land. When surface water moves through wetlands adjacent to water courses,
flood flows are temporarily retained by dense stands of vegetation in wetlands
and slowly released downstream.

Water Supply
Wetlands may also provide a domestic or commercial supply of water. Flood
waters may flow from wetland into a ground water aquifer and recharge it.
For example, a five-square-mile bog in Wisconsin controls the groundwater
supply for a 165- square-mile area.

Sediment and Erosion Control
Wetlands maintain water quality by controlling erosion and sedimentation.
Vegetative cover over the soil will absorb most of the shock from the impact
of the water, so it is less likely to loosen soil. Sediment carried by
runoff will tend to be trapped in wetlands and held by ground vegetation.
In shallow waters, submerged aquatic vegetation acts as a filter, as sediment
clings to plants instead of floating in the water. Aquatic plants also
reduce water velocity, so additional sediment tends to sink to the bottom
instead of floating freely. Shoreline vegetation decreases the force of
wave action and reduces erosion in tidal areas.

Nutrient Retention and Removal
Wetlands remove nutrients such as nitrogen and phosphorus from the environment.
Wetland plants absorb the nutrients for their own growth, making them unavailable
to algae. Without this absorption, algae blooms in open water may grow
and dominate the system so that little oxygen is available for other aquatic
life. Wetlands efficiently remove nutrients but cannot remove all of them.
The algae blooms in the Chesapeake Bay result from nutrient “overload,” beyond
the capacity of the wetlands and aquatic plants to remove all of them.

Pollution Control
Wetlands filter pollutants and treat sewage. Heavy metals accumulate in wetland
soils, not plants or water which may be consumed by people or wildlife.